1. Field of Invention
Exemplary embodiments of the present invention relate to an electronic device, and more particularly, to a semiconductor memory device and a method of operating the same.
2. Description of Related Art
A semiconductor memory device may be divided into a volatile memory device or a non-volatile memory device.
The volatile memory device may lose data stored therein if supplying of a power is stopped, and may perform a read/write operation at a high speed. Meanwhile, the non-volatile memory device may retain the stored data even when the power is not supplied, but tends to have a lower speed than the volatile memory device in the read/write operation. Accordingly, the non-volatile memory device is used to store data to be maintained irrespective of supplying of the power. The non-volatile memory device may include a read only memory (ROM), a mask ROM (MROM), a programmable ROM (PROM), an electrically programmable ROM (EPROM), an electrically erasable and programmable ROM (EEPROM), a flash memory, a phase-change random access memory (PRAM), a magnetic RAM (MRAM), a resistive RAM (RRAM), a ferroelectric RAM (FRAM), etc. There are two main types of the flash memory device: a NOR-type flash memory and a NAND-type flash memory.
A flash memory has an advantage of the RAM for being programmable and erasable data and an advantage of the ROM for maintaining the stored data even when the power is blocked. The flash memory is widely used as a storage medium of a portable electronic device such as a digital camera, a personal digital assistant (PDA) and an MP3 player.
Reliability of data of the semiconductor memory device, for example, the flash memory, may be deteriorated due to various causes.
Accordingly, a semiconductor memory device with high reliability of data is in demand.